Syrian government forces take down an Islamic State flag on Feb. 21, 2016, after winning control of eastern Aleppo from the terrorist group. Some observers note ISIS has not recorded a major military victory in months, but others say the United States and its allies are still far from defeating the terrorists. (AFP/Getty Images/George Ourfalian)

Since emerging out of the conflicts in the Middle East, the self-proclaimed Islamic State (ISIS) has become the leading instigator of global terrorism, including deadly bombings in Brussels and Paris. ISIS proclaims devotion to a radical version of Islam, and it has imposed a brutal dictatorship in areas it controls in Syria and Iraq. It also has initiated or inspired terrorist attacks in places as far-flung as Indonesia and California. The United States and a coalition of nations have committed themselves to defeating ISIS. However, the Islamic State has proven more resilient than many predicted, leading to a contentious debate over strategy. Some political leaders are calling for an increased U.S. military effort, including use of ground troops. Others believe the approach would increase ISIS' popularity and lead to further attacks in the West. Governments also are struggling to counter ISIS' propaganda and recruiting efforts, both of which rely on a sophisticated use of the Internet.